So if you have mass/bulk unknown friends on your Facebook Account and want to delete/unfriends all those in one click than follow the given below steps and you are done.
1.Download this simple FacebookDeletes Script on your Chrome browser.
If you are using Firefox you have to install a Greasemonkey in your Firefox browser.Than install this FacebookDeletes Script.
2.After downloading this script open the Facebook Friends Page where you will see all your friends.
3.Now Select those friends whcih you want to delete in bulk and than click on
Facebook Delete Friends: button and than unfriend your friends from your list.
4.Finally You are done.